The present invention relates to an automatic document handling apparatus and more specifically to a recirculating document feeder circulating original documents to and from an imaging zone of a copying machine, the recirculating document apparatus being capable of accommodating both simplex and duplex copying.
Heretofore, it has been known to recirculate an original document in a manner which satisfies both simplex and duplex copying such as disclosed in U.S. Pat. No. 4,238,126. A recirculating document handler for both simplex or duplex copying implements fixed platen copying which includes a first oval shaped document return path which directs the original over the platen through a first conveyor path and returns the original to a document containing cassette, reversing the document for duplex copying, and a second document or conveyor path provided diagonally between the document path for duplex copying and the platen or imaging zone for returning documents after copying from the discharge or exiting end of the platen directly to the document containing cassette, without reversal of the document, to satisfy the simplex copying mode. While this apparatus has been found to be useful in recirculating document handlers, it has certain disadvantages. In the first instance in order to accommodate duplex copying, the reversed original must be returned to the top of the stack of documents in the document cassette and await return to the imaging zone while the remainder of the originals go on imaging, thus delaying duplex copying of a particular original. Accordingly, the configuration does not provide for immediate or direct duplex copying if desired. Furthermore, due to the fact that all of the paths returning the original document to the document cassette originate from the discharge side of the fixed platen the overall required size and complexity of the document handler is substantially increased. In addition, the return path for accommodating the simplex copying mode is provided between the exposure station of the fixed platen and the duplex copying return path. Therefore, if a paper jam occurs, it is very difficult to access the respective paths for clearing the jam.
In still a further apparatus for recirculating a document to be copied in either the simplex or duplex copying mode, an apparatus has been designed as taught by European Patent 0078,680 having a duplex copying path and a simplex copying path similar in location to that of U.S. Pat. No. 4,238,126. However, in the case of the latter apparatus, the second conveyor path for returning the original document in the case of simplex copying, to the document cassette, extending from the discharge side of the exposure platen diagonally in the direction of the top of the cassette above the imaging zone between the platen and the first duplex copying return path, includes a second return path for directly returning the original to the exposure platen, with reversal of the original for direct duplex copying. Thus, the combination of the diagonal conveyor path and the second return path for directly returning the reversed original to the exposure platen, extending from the discharge or second side of the exposure platen to the feed or first side of the exposure platen, are positioned between the first conveyor path through the exposure zone over the exposure platen and the first duplex copying return path. In this apparatus, the original to be copied is capable of moving through a first conveyor path directly over the exposure platen forming the exposure zone, and through a first return path which returns the reversed original document to the top of the document cassette for delayed duplex copying, the return path being situated above the first conveyor path. The apparatus is also capable of transporting the exposed original through the diagonally positioned second conveyor path either directly to the document cassette during simplex copying or through the second return path back to the exposure platen for direct duplex copying, this combination of paths being situated between the first conveyor path above the exposure platen and the first return path. Yet, while the latter document recirculating apparatus provides for direct duplex copying, due to the nature of the positioning of the document paths, each of which must be separately accessible, and complexity of the construction, it still remains extremely difficult to clear a document jam.